This invention relates to a keyboard musical instrument and, more particularly, to a composite keyboard musical instrument equipped with a hammer stopper for muting acoustic tones.
An acoustic piano is equipped with an electronic sound generating system and a silent system, and is a kind of composite keyboard musical instrument for selectively generating electronic tones and acoustic tones. A hammer stopper is an essential part of the silent system. When an acoustic piano is retrofitted to the composite keyboard musical instrument, the hammer stopper is usually installed in the space between the hammer shanks and the music strings. The hammer stopper is changeable between a free position and a blocking position. When a pianist wishes to play a tune on the composite keyboard musical instrument through the acoustic tones, the hammer stopper is changed to the free position. The hammer stopper permits the hammers to strike the associated strings, and the strings generate the acoustic tones. On the other hand, if a pianist wishes to practice fingering on the keyboard without acoustic tones, the pianist changes the hammer stopper to the blocking position. Eve though the hammers are driven for rotation by the action mechanisms, the hammers rebound on the hammer stopper before striking the strings, and any acoustic tone is generated from the strings. The key action or the hammer action is monitored by an array of sensors, and electronic tones are generated by the electronic sound generating system. The pianist hears the electronic tones through a headphone, and records the pieces of music data information representative of the practice in a suitable information storage medium. Thus, the pianist can practice the fingering without disturbance of the neighborhood.
In the following description, term xe2x80x9clateralxe2x80x9d is indicative of a direction in which black keys and white keys are laid on the well-known pattern, and term xe2x80x9cfore-and-aftxe2x80x9d is indicative of the direction perpendicular to the lateral direction. Term xe2x80x9cfrontxe2x80x9d is indicative of a position closer to a pianist who plays a tune on a composite keyboard musical instrument than a xe2x80x9crearxe2x80x9d position.
FIGS. 1 and 2 show a typical example of the hammer stopper installed in an acoustic grand piano. The hammer stopper is designed to make the hammer shanks 1a to rebound thereon in the blocking position. The prior art hammer stopper largely comprises a shaft 2a, brackets 2b and laminations of artificial leather sheets 2c, and is connected through a link work 3 and a flexible wire 4 to a pedal (not shown). The shaft 2a laterally extends in the space between an array of hammers 1 and sets of strings 6, and is angularly movable about the center axis thereof. The brackets 2b are attached to the shaft 2a at intervals, and the artificial leather sheets 2c are laminated on the brackets 2b. 
The link work 3 is turnable about the center axis of a pin 3a, and the flexible wire 4 is connected to the link work 3. The flexible wire 4 extends downwardly, and is terminated at the pedal (not shown). The pedal is supported by a lyre box (not shown) together with the other pedals, i.e. a damper pedal and a soft pedal. Otherwise, the flexible wire 4 extends frontward, and is terminated at a grip (not shown) attached to the back surface of the key bed (not shown). When the pianist changes the hammer stopper from the free position to the blocking position, he or she steps on the pedal, and pulls down the flexible wire 4. If the flexible wire 4 is terminated at the grip instead of the pedal, the pianist frontward pulls the flexible wire with the grip. The pianist is to move the pedal or the grip between the dead points. Then, the other end of the flexible wire 4 is downwardly moved, and the Link work 3 is driven for rotation about the center axis of the pin 3a. Accordingly, the shaft 2a is angularity moved about the center axis thereof. The laminations of artificial leather sheets 2c are out of the trajectories of the hammer shanks 1a in the free position as indicated by dots-and-dash line. When the hammer stopper 2 is changed from the free position to the blocking position, the laminations of artificial leather sheets 2c enter the trajectories of the associated hammer shanks 1a through the angular motion, and the laminations of artificial leather sheets 2 are opposed to the hammer shanks 1a as indicated by real lines in FIG. 1.
As known to the skilled person, black/white keys 7 are laid on the well-known pattern of keyboard, and notes of the scale are respectively assigned to the black/white keys 7. The notes are also assigned to the associated sets of strings 6, respectively. Action mechanisms 8 are provided between the black/white keys 7 and the hammers 1. The hammers 1 are rotatably connected to hammer shank flanges, which in turn are fixed to a shank flange rail. When a pianist wishes to generate a piano tone, he or she depresses the black/white key 1 assigned the note identical with the piano tone to be generated. The depressed key 7 gives rise to rotation of the action mechanisms, and the action mechanism 8 escapes from the associated hammer 1. When the action mechanism 8 escapes from the associated hammer 1, the hammer 1 is driven for rotation about the hammer shank flange. If the hammer stopper 2 is in the free position, the hammer 1 strikes the associated set of strings 6 with the hammer head 1b, and the piano tone is radiated from the vibrating strings 6. On the other hand, if the hammer stopper 2 has been changed to the blocking position, the hammer shank 1a is brought into contact with the lamination of artificial leather sheets 2 (see FIG. 3) before reaching the set of strings 6, and rebounds thereon.
Thus, the prior art silent system allows the pianist to play a tune on the keyboard through the acoustic tones or the electronic tones in so far as he or she surely moves the hammer stopper 2 between the dead points. However, if the pianist stops the pedal or grip at an intermediate point between the dead points, the hammers 1 are liable to damage the hammer stopper 2 or be damaged at the impact against the hammer stopper 2.
In case where the pianist changes the hammer stopper 2 from the free position to the blocking position before the performance, he or she can concentrate his or her attention on the manipulation of the pedal/grip. However, when the pianist changes the acoustic tones to the electronic tones during the performance, he or she is to manipulate the pedal or grip concurrently with the fingering on the keyboard. If the pianist proceeds to complicated music passage during the manipulation, he or she tends to have his or her attention distracted, and is liable to stop the pedal or grip an intermediate point between the dead points.
Another problem is poor manipulability of the hammer stopper 2 due to a time lug between the manipulation of the pedal or grip and the completion of the angular motion. As described hereinbefore, the flexible wire 4 interconnects the link work 3 and the pedal or grip. The link work 3 is provided over the rear portions of the black/white keys 7, and the pedal or grip is located at the lyre box or immediately under the keyboard. Therefore, the flexible wire 4 is not short. When the pianist exerts tension on the flexible wire 4 by means of the pedal or grip, the flexible wire 4 is elastically deformed, and, thereafter, slides in the guide tube. The elastic deformation introduces the time lug into the power transmission from the pedal or grip to the link work 3. The pianist has to take the time lug into account. In other words, when the pianist wishes to change the hammer stopper 2 from the free position to the blocking position, he or she is to initiate the manipulation of the pedal or grip before the first note to be electronically generated. However, it is quite difficult exactly to adjust the change to the blocking position to the first note. In an actual performance, it is recommended for the pianist to change the hammer stopper in a relatively long rest in a music score.
It is therefore an important object of the present invention to provide a composite keyboard musical instrument, the silent system of which is promptly responsive to user""s manipulation.
In accordance with one aspect of the present invention, there is provided a keyboard musical instrument comprises an acoustic keyboard musical instrument including a keyboard consisting of plural keys, plural vibratory members vibrating for generating acoustic tones respectively assigned notes of a scale, plural vibration generating mechanisms respectively provided between the plural keys and the plural vibratory members and responsive to motions of the plural keys for generating vibrations in the plural vibratory members and a case accommodating the plural vibratory members and the plural vibration generating mechanisms and providing the keyboard to a player, and a silent system including an actuator generating a power, a stopper changed between a free position for allowing the plural vibration generating mechanisms to generate the vibrations in the plural vibratory members and a blocking position for preventing the plural vibratory members from the plural vibration generating mechanisms and an interconnection connected between the actuator and the stopper and rigid against the power so as to promptly transmit the power from the actuator to the stopper without substantial deformation thereof.
In accordance with another aspect of the present invention, there is provided a keyboard musical instrument comprises an acoustic keyboard musical instrument including a keyboard consisting of plural keys, plural vibratory members vibrating for generating acoustic tones respectively assigned notes of a scale, plural vibration generating mechanisms respectively provided between the plural keys and the plural vibratory members and responsive to motions of the plural keys for generating vibrations in the plural vibratory members and a case accommodating the plural vibratory members and the plural vibration generating mechanisms and providing the keyboard to a player, and a muting system including an actuator generating a power, a stopper changed between a free position for allowing the plural vibration generating mechanisms to generate the vibrations in the plural vibratory members and a muting position for reducing forces exerted on the plural vibratory members by the plural vibration generating mechanisms and an interconnection connected between the actuator and the stopper and rigid against the power so as to promptly transmit the power from the actuator to the stopper without substantial deformation thereof.